1. Field of Invention
The current invention relates to security tags and more particularly, to re-usable security tags that can be used with containers such that an RF receiver is able to readily discern a return signal from the tag.
2. Description of Related Art
The prior art teaches various mechanisms of using security tags to secure a multitude of different products. Some examples of commonly known security tags are RF (radio frequency), AM (acousto-magnetic) tags and EM (electromagnetic) tags, traditionally known as electronic article surveillance (EAS) tags. Other security tags, e.g., radio frequency identification (RFID) tags, including UHF (ultra-high frequency) tags, make use of electronic integrated circuits. EAS, RFID and other types of electronic security tags can be and are used mounted or secured to many different products, e.g., books, pallets, containers, and electronics.
Currently, products that are housed in containers or cans having metallic portions, e.g., containers or cans for baby foods and other foodstuffs, etc., have not been effectively tagged. As will be appreciated by those skilled in the art, many containers for foods are made of plastic. However, plastic has inherent limitations for housing such products. For example, plastic may allow trace amounts of bacteria through it. Baby food manufacturers are particularly sensitive to the limitations of plastics as a container medium and consequentially, many such manufacturers make their containers or cans out of cardboard tubular midsection having a pressed, thin aluminum foil around the outside of the midsection as a means for preventing liquid leakage out of the container. Additionally, the lid and the base of the can or container are generally made of a thin aluminum sheet. A relatively thick, annular aluminum ring serves to join the lid to the cardboard midsection, a similar ring serves to join the base to the cardboard midsection. This arrangement provides an inexpensive, easily manufactured, waterproof container that can safely hold foodstuffs. However, such containers also include so much metal that they cannot be effectively tagged with an EAS, RFID or other electromagnetic radiation-based tag, since the metal of the container will interfere with the electromagnetic properties of the tag, e.g., the metal portion of the can will reduce the amplitude of the return signal from the tag. Moreover, the metallic portion of the container also tends to act as an antenna, thereby altering the frequency response of the tag.
Furthermore, many EAS tags used in retail establishments are termed “hard tags,” which refers to a re-usable tag which is intended to be removed from an article, e.g., merchandise, at the point of sale (POS) to be re-used on other merchandise. Hard tags typically have an injection-molded outer casing. This type of tag is typically found in the apparel industry. U.S. Pat. No. 4,940,968 (DeNood) and U.S. Patent Publication No. 2004/0233042 (Piccoli, Anthony, F., et al.), both of whose entire disclosures are incorporated by reference herein, disclose various exemplary hard tag embodiments.
Thus, a need exists for a re-usable security hard tag which enables the effective tagging of containers, including those with substantial metallic portions, e.g., baby food containers, soup containers, etc.
All references cited herein are incorporated herein by reference in their entireties.